The present invention relates to a highly soluble sweetener composition containing Aspartame (hereinafter abbreviated as xe2x80x9cAPMxe2x80x9d) and Acesulfame K (hereinafter abbreviated as xe2x80x9cACE-Kxe2x80x9d) as active ingredients.
It is reported that the level of sweetness of APM which is an amino acid-based synthetic sweetener, is about 200 times that of sucrose in terms of weight ratio (Japanese Patent Application Publication (Kokoku) No. 31031/""72). When compared with sucrose which is regarded as a standard for evaluating sweetness characteristics, the profile of sweetness characteristics of APM is of such that it is weak in early taste (which means that the sweetener when placed in the mouth does not taste sweet so early as sucrose does), whereas it is strong in late taste (which means that the sweetener when placed in the mouth tastes sweet later than sucrose does). Accordingly, various approaches for the improvement of the sweetness profile of APM have been proposed mainly in terms of the late taste (for example, Japanese Patent Application Laid-open (Kokai) Nos. 148255/""81, 141760/""83, 220668/""83 and the like), and a method for obtaining a more natural sweetness profile which is closer to that of sucrose, for example, by using APM in combination with sucrose has been also proposed (Japanese Patent Application Laid-open (Kokai) No. 152862/""82).
On the other hand, ACE-K is also a synthetic sweetener having a sweetness level of about 200 times that of sucrose, like APM, but has such further poorer sweetness profile that it is strong in early taste, bitter taste, astringent taste, peculiar taste, and stimulation when compared with APM. Therefore, it has been subjected to various approaches for the improvement, including the use in combination with APM for improving the sweetness profile (U.S. Pat. No. 4,158,068, and corresponding Japanese Patent Application Publication (Kokoku) No. 51262/""84). For example, the Japanese Patent Application Publication discloses the concurrent use of ACE-K and APM in a (weight) ratio of about 1:10 to 10:1, especially about 2:5 to 5:2, which, in turn, provides a sweetness profile closer to that of sucrose than that of either of the two.
Thus, various proposes have been made for improving the sweetness profile of APM, and each has been successful to some extent. Nevertheless, APM involves still such other problem concerning its solubility characteristics that an industrially produced APM powder (original crystals) is difficult to dissolve in water (because it has a tendency to form agglomerates (in Japanese, dama) and therefore, is not smooth to dissolve, and even without that, it has a lower rate of dissolution, and the like). The poorer solubility (i.e., poorer dissolution rate) due to such agglomeration and the like leads to the reduction in the production efficiency of food products or beverages to be supplemented with APM for imparting sweetness thereto, including soft drinks, which is, in turn, greatly disadvantageous to the commercial production thereof.
Some approaches for improving the solubility of APM have been proposed, including a method of graining (granulation). However, these approaches are still not satisfactory, e.g., because the solubility needs further improving (Japanese Patent Application Laid-open (Kokai) No. 346769/""92, and the like) and because a relatively larger amount of an excipient should be used concomitantly (Japanese Patent Application Laid-open (Kokai) Nos. 126855/""74, 19965/""75, 150361/""82, and the like). Incidentally, the concurrent use of ACE-K with APM disclosed in the above-mentioned Japanese Patent Application Publication (Kokoku) No. 51262/""84 is a concurrent use by merely mixing aqueous solutions of the two components (i.e., an aqueous ACE-K solution and an aqueous APM solution), and there is not made in the patent document any suggestion of the concurrent use of the two components, both in the form of original crystals or granules, nor any mention of the solubility of either of the two in the original crystals or granular form.
In view of the prior art discussed above, it is an object of the present invention to provide an excellent method for improving the solubility of APM.
The present inventors have made an effort to achieve the object described above and found unexpectedly that, in the presence of untreated crystals of ACE-K or a product resulting from pulverizing the untreated crystals (hereinafter abbreviated as xe2x80x9cpulverized ACE-Kxe2x80x9d), untreated crystals or granules of APM undergo no agglomeration during dissolution (in water) and exhibit a higher dissolution rate as compared with the case of APM alone, i.e., that APM is on the whole improved in solubility, thus establishing the present invention.
Accordingly, the present invention relates to a sweetener composition comprising Aspartame and Acesulfame-K as active ingredients, wherein the amount of Acesulfame-K is 5 to 90% by weight based on the total amount of both the components and wherein the particle sizes of both the components are respectively selected from within the range of the particle size which allows the dissolution rate of the mixture to be higher than that of Aspartame alone.
The present invention will be further described in greater detail below.
APM, which is one of the active ingredients of a sweetener composition of the present invention, can be a commercially available untreated crystalline powder (untreated crystals) as it is or granules having a larger particle size made by granulating such untreated powder. While it is known that APM is imparted with an improved solubility when it is granulated (Japanese Patent Application Laid-Open (Kokai) No. 346769/""92, described above), it has been found by the present inventors that the solubility of such granules can be further improved in the presence of ACE-K. Furthermore, it has been found that APM can be still imparted with a higher solubility in the presence of ACE-K also when it is in the form of untreated crystals.
Granules of APM can be produced by granulating an APM original crystalline powder. The granulation is not particularly limited, and can be conducted in accordance with a known method. For example, a dry granulating process and also a wet granulating process can be employed. Specifically, granules can be produced by various methods such as mixing granulation, compacting granulation, extrusion granulation, fluidization granulation, rotation granulation, pulverization granulation, spray coating, tabletting or the like. However, for the purpose of less heat load and less complicated manufacturing process, it is commercially advantageous to employ a dry granulation process such as compacting granulation.
ACE-K which is the other active ingredient of a sweetener composition of the present invention can be incorporated in the sweetener composition as untreated crystals as they are or after being pulverized (i.e., in the pulverized form).
An untreated crystalline powder of ACE-K can be prepared by a known method and converted into one having a desired particle size by means of crystallization and, if necessary, pulverization.
The mixing ratio (ratio of amounts employed) of APM and ACE-K in a sweetening composition of the present invention is appropriate when the ACE-K is present in an amount of 5 to 90% by weight based on the total amount of both the components. Incidentally, an ACE-K content of 5% by weight or less provides almost no dissolution-promoting effect by ACE-K, while that of 90% by weight or higher causes the bitter taste of the ACE-K to get evident, which is of course undesirable.
Even with a mixing ratio between APM and ACE-K specified above, the dissolution-promoting effect by ACE-K on APM varies depending on the particle sizes of APM (untreated crystalline powder or granule) and ACE-K (untreated crystalline powder or pulverized product). Too small particle size of APM may cause formation of agglomerates (in Japanese, dama) and may cause the APM to float on the surface of water instead of being dispersed in water, which may, in turn, take a prolonged time period for dissolution, while a too large particle size of the granules may result in a reduction of the interface area where the particles and the water are in contact, which may, in turn, take a prolonged time period for dissolution. APM to float on the surface of water instead of being dispersed in water, which may, in turn, take a prolonged time period for dissolution, while too a large particle size of the granules may result in a reduction in the interface area where the particles and the water are in contact, which may, in turn, take a prolonged time period for dissolution.
An improvement in the solubility of APM as a result of admixing ACE-K is due to the prevention thereby of the agglomeration of APM and the prevention thereby of the floating of APM on the surface of water, and a more thorough mixing of both the components provides a higher effect. A higher effect is obtained with a smaller particle size of ACE-K since a more thorough mixing is possible. ACE-K whose true specific gravity is 1.85 (in contrast to 1.36 of APM) exhibits a satisfactory sedimentation, and its high solubility allows fine particles, which tend to float, to be readily dissolved and disappear. Incorporation of ACE-K also reduces the floating of APM on the liquid surface. A higher effect by a smaller particle size of APM is due not only to a more thorough mixing but also to the prevention of the agglomeration and the prevention of the floating on the liquid surface, and to the fact that larger particles limit the dissolution rate.
As has been described above, ACE-K exhibits a higher dissolution-improving effect on APM when its particle size is smaller, and the average particle size is preferably about 250 xcexcm or less. The maximum particle size is preferably about 500 xcexcm or less, and more preferably about 250 xcexcm or less. ACE-K having such a small particle size can be readily prepared by pulverizing an ACE-K untreated crystalline powder by a known appropriate method. While APM exhibits a higher solubility when it is in the granule form than when it is in the untreated crystalline powder, an excessively large particle size poses a prolonged time period required for dissolution as described above, and the average particle size is preferably about 500 xcexcm or less.
In a given case, the particle size of ACE-K which exerts a marked dissolution-promoting effect on APM can be determined as a particle size of ACE-K in the admixture with which a given untreated crystalline powder (untreated crystals) or given granules of APM can exhibit a significantly improved dissolution rate (time period required for dissolution) as compared with the dissolution rate of the same APM untreated crystalline powder (untreated crystals) in the same quantity as contained in the above mixture when tested alone (see Experiment 1, last paragraph, described below). It is a matter of course that such particle size of ACE-K for a given APM untreated crystals can be readily determined by those skilled in the art by performing a preliminary test.
Incidentally, when APM and ACE-K having inventive particle sizes are placed in water separately but simultaneously (separate addition) without mixing previously at an inventive ratio (as in the case of an inventive sweetening composition), ACE-K having a high dissolution rate dissolves rapidly and prevents the dissolution rate of APM from being dependent on the particle size of ACE-K, resulting in the dissolution rate of APM as a sole component (Experiment 3 described below).
The inventive sweetener composition can, depending on its use, contain a diluent or an excipient such as a sugar alcohol, an oligosaccharide and a dietary fiber as well as other high intense synthetic sweetener(s) such as Alitame, Saccharin, 3,3-dimethylbutylaspartylphenylalanine methylester and the like, like in the case of conventional intense synthetic sweetener compositions, for the purpose of obtaining a better handling or improving the sweetness profile, as long as the improved solubility of APM according to the present invention is not affected adversely. A diluent or an excipient referred to herein includes a low intense sweetener such as sucrose, glucose and the like.
The solubility of APM granules (i.e., granules consisting of APM alone) as disclosed in the above-mentioned Japanese Patent Application Laid-open (Kokai) No. 346769/""92, is just less unsatisfactory than that of an APM original powder, and further improvement of the solubility is demanded by users. In accordance with the present invention, such further improvement of the solubility of APM has been realized, and also an excellent sweetener can be produced in which the sweetness profiles of both of APM and ACE-K are improved.